Gambit-list Février 2008

gambit-list@iro.umontreal.ca

29 participants
37 discussions

Move definitions of string=? and string-ci=? to _system.scm
by Bradley Lucier 23 Fév '08

23 Fév '08

Marc: The tables implementation has special hash functions for these common tests: eq?, eqv?, equal?, string=?, string-ci=? The table access routines and the special has functions are defined in _system.scm. The tests themselves are defined in the following: _system.scm: eqv?, eq?, equal? _std.scm: string=?, string-ci=? So tables that use string=? for a hash function have to do two extra intermodule calls per table lookup; that may be why string=? tables are currently noticeably slower than eq? tables. Brad

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Programming language shootout benchmark programs
by Bradley Lucier 22 Fév '08

22 Fév '08

Motivated by a blog for the GHC Haskell compiler, I've added programs for the Computer Language Benchmarks Game http://shootout.alioth.debian.org/ to the Gambit Wiki, starting at a new benchmarks page here: http://dynamo.iro.umontreal.ca/~gambit/wiki/index.php/Benchmarks Knock yourself dead improving these if you like, or on filling in the gaps; I plan to submit something for these benchmarks after 4.2.3 is released. (I'm waiting because there are several bug fixes in the compiler that speed up some of these benchmarks considerably.) Brad

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read-subu8vector
by Guillaume Cartier 22 Fév '08

22 Fév '08

In my web-server when I receive a request, the code to parse that request that is very natural goes something like : - read-line until received an empty line to read the headers - read-subu8vector to read the body that could be anything Problem is that the doc states that read-subu8vector should *not* be used after character input operations have been done on the port because otherwise the character-stream and byte-stream may be out of sync due to the port buffering. Is there any work around this limitation? (of course it is possible to modify the code not to do any character input operations but it becomes less elegant) Thanks, Guillaume Cartier

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read-subu8vector
by Jeremie Lasalle Ratelle 21 Fév '08

21 Fév '08

> (define vect (make-u8vector 3)) > (call-with-input-string "string" (lambda (pt) (read-subu8vector vect 0 2 pt))) *** ERROR IN call-with-input-string -- Input port character buffer is not empty (read-subu8vector '#u8(0 0 0) 0 1 '#<input-port #2 (string)>) read-subu8vector calls macro-lock-and-check-input-port-character-buffer-empty I guess it's a bug since I don't see what would be the use. Or enlighten me...

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Integer infinity?
by David St-Hilaire 21 Fév '08

21 Fév '08

Hi gambit-list! I'd like to know how can I compare an exact number with the +/- infinity value... I've found that there is +inf.0 available for inexact numbers, but a simple (exact->inexact +inf.0) does not seem to work :(. Thank you! ^_^ David

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Termite problems
by Nicholas Walton 19 Fév '08

19 Fév '08

Hi, I've just started working with Termite to distribute the processing for a large data mining system over a multi core CPU and I seem to be hitting a few problems for which any advice is welcome. Small scale examples seem to work well but once I scale up I hit problems. I'm running on a 1Gig Mac using OS X 10.4 with the latest distribution of Gambit and the current tarball from the Termite site together with the slib library. At first I built a two process client server example but it hung. The problem turned out to be the array.scm file in the slib distribution redefining the equal? procedure. Once the redefinition was removed all worked well. So long as I used tags and not pids to identify one remote process to another. The pid returned by remote-spawn is not the same as that returned by the process calling (self). I then moved on to trying a parallel version of map, akin to that given at http://theschemeway.blogspot.com/2007/06/parallel-map-with-termite.html . That worked fine for small simple examples but when I threw in a larger example, evaluating forty instances of a k-means cluster procedure in parallel in one process, it consistently dumps core but not in any predictable manner. All forty threads kick off fine but while some succeed others fail catastrophically and at no particular point resulting in Gambit dumping core. I've run the code using map and all was well, and the code has nothing in it which seems likely to cause the problem. I've run the code both compiled and fully interpreted and the behavior is the same. First is there any changes to the Gambit build which might help identifying where the fault is occurring? Secondly are there known problems with Termite especially when spawning moderately large processes.? Many Thanks Nick Walton

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Questions about tables.
by Bradley Lucier 19 Fév '08

19 Fév '08

Marc: I have some questions about tables. 1. Can there be a function like (table-update! table key (lambda (#!optional (value default-value)) <whatever>)) instead of using (table-set! table key ((lambda (value) <whatever>) (table-ref table key default-value))) It would seem to avoid one table lookup for the key. 2. I presume that the table can get messed up if the keys are mutable and you change the key (like a string) after it has been used to index the table. Or is it possible to tell the table to copy any keys that are not in the table as they are entered into the table? Brad

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Namespaces
by jadamson＠partners.org 13 Fév '08

13 Fév '08

Hello Gambitious Schemers, I've read the Wiki Namespaces page and I'm still trying to figure out how to incorporate the information. Here's my situation: * I have copied ~~/syntax-case.scm to ~~/gambcext.scm since I want to use some syntax-rules macros * I compile a file that "include"s all the relevant files and then includes a funny message: ;;;test.ss (include "c-header.ss") (include "scheme-header.ss") (include "gsl_structures.ss") (include "gsl_lalgebra.ss") (include "gsl_wrapper.ss") (include "f64matrix.ss") (include "life-table.ss") ;;includes ;;(define-structure life-table gens m p a) (define C (make-f64matrix 2 2 (f64vector 8.67 53.09 3.14 2.17))) (define C-gsl (make-gsl-matrix 2 2 (f64matrix-data C))) (define C->gsl (f64matrix->gsl-matrix* C)) (define vec2 (f64vector 1.0 1.0)) (define tbl (make-life-table '(1 2) '(5 10 20) '(0.5 0.75 0.9) '(0.5 0.5 0.5))) (display "Good evening, Dave. Everything's running smoothly, and you?") (newline) I compile this with: # a rudimentary Makefile for Gambit targets LDOPTS="-g -L/usr/lib/gsl -lgslcblas -lgsl" CCOPTS="-I/usr/include" GSCOPTS=-keep-c -debug -track-scheme -warnings -expansion libs = gsl_lalgebra.ss gsl_wrapper.ss f64matrix.ss test: gsc $(GSCOPTS) -ld-options $(LDOPTS) -cc-options $(CCOPTS) test.ss Everything compiles just fine. * I "run-scheme" in Emacs, and then the action happens: Gambit v4.2.0 > (load "test") Good evening, Dave. Everything's running smoothly, and you? "/home/joel/lisp/scm/population/libgenx/test.o11" > ##make-life-table *** ERROR IN (stdin)(a)2.1 -- Unbound variable: ##make-life-table 1> ,t > make-life-table *** ERROR IN (stdin)(a)4.1 -- Unbound variable: sc#make-life-table 1> ,t > sc#make-life-table *** ERROR IN (stdin)(a)6.1 -- Unbound variable: sc#make-life-table 1> * So, what's going on here? What namespace is my structure attached to? Do I need to define namespaces in my files to be able to access these things from the REPL (and in future code)? * The wiki page mentions something about the namespace functions not being supported in the future. What is the status of the namespace mechanism supported or not? Will it be in the future? It seems like I need to use it if I am going to use syntax-case, or will that change too? Thanks, Joel -- Joel J. Adamson Biostatistician Pediatric Psychopharmacology Research Unit Massachusetts General Hospital Boston, MA 02114 (617) 643-1432 (303) 880-3109 The information transmitted in this electronic communication is intended only for the person or entity to whom it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this information in error, please contact the Compliance HelpLine at 800-856-1983 and properly dispose of this information.

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bugzilla is stale
by Bradley Lucier 12 Fév '08

12 Fév '08

Marc: I just went through gambit's list of "bugs" in bugzilla and closed a bunch of them since it appears that they've been fixed since the bugs were first reported. I think it would be good if bugzilla could be the place where bugs are introduced and discussed, where *patches related to those bugs are posted* (or at least a link made to the mercurial patch that fixes them), where bugs are closed, etc. Having a stale bugzilla doesn't help gambit development. (And it would be better if you personally were to submit comments on bugzilla as "feeley" rather than the omniscient and omnipotent "gambit", so that people would know who the man is behind the curtain that is talking to them.) Brad

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Embedding a REPL in an executable
by Neil Baylis 11 Fév '08

11 Fév '08

I'm building an executable that links with an object file that controls a machine via the USB bus. I have this working OK by linking everything into an executable. But that means I must recompile every time I make a change to my scheme code. Instead, I'd like to be able to load the scheme code at runtime. Originally I wanted to compile my c code into a library so that I could load it with gsi. However i was unable to get that to work. Poking around in the examples, I found (##repl-debug-main), so I put that at the end of my c-api .scm file. This works well. When I run the executable, I get a repl, and can then load further scheme files as needed. Is this the recommended way to embed a Gambit repl in a c program? Where can I find this ##repl-debug-main documented? What's the significance of the ## character? Is there a way to pass startup arguments to this repl? Thanks, Neil Baylis -- http://www.pixpopuli.com

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Gambit-list Février 2008